Regression of cetacean tattoo lesions concurrent with conversion of precipitin antibody against a poxvirus.

Tattoo lesions linked to the cetacean poxvirus of bottlenose dolphins regressed without treatment. Two types of regression were observed: (1) The tattoo lesions became raised and blanched, then disappeared along with sloughing skin. (2) When an incision was made through a tattoo lesion, the tattoo disappeared in a zone around the incision. Poxviruses removed from the raised, blanched skin lesions and from typical tattoo lesions were reacted with dolphin serums and examined by immunoelectron microscopy. Antibody was not detected against either of these poxvirus preparations when the dolphins had only typical tattoo lesions. However, after the raised, blanched lesions appeared, serums obtained during the acute or convalescent stages were positive for the poxvirus separated from the lesions. Regression of the typical tattoo lesions was concurrent with antibody conversion.